IEEE 802.15 <PHY Proposal>

1
Project IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs) Submission Title
Merged UWB proposal for IEEE 802.15.4a
Alt-PHY Date Submitted 22 Feb 2005 Source
Francois Chin, et.al. Company Institute for
Infocomm Research, Singapore Address 21 Heng
Mui Keng Terrace, Singapore 119613 Voice
65-68745687 FAX [phone] E-Mail
chinfrancois_at_i2r.a-star.edu.sg Re Response
to the call for proposal of IEEE 802.15.4a, Doc
Number 15-04-0380-02-004a Abstract Merged
Proposal to IEEE 802.15.4a Task
Group Purpose For presentation and
consideration by the IEEE802.15.4a committee
Notice This document has been prepared to
assist the IEEE P802.15. It is offered as a
basis for discussion and is not binding on the
contributing individual(s) or organization(s).
The material in this document is subject to
change in form and content after further study.
The contributor(s) reserve(s) the right to add,
amend or withdraw material contained
herein. Release The contributor acknowledges and
accepts that this contribution becomes the
property of IEEE and may be made publicly
available by P802.15.
2
This contribution is a technical merger between

• Institute for Infocomm Research 05/032
• General Atomics 05/016
• Thales Cellonics 05/008
• KERI SSU KWU 05/033
• Create-Net  China UWB Forum 05/019
• Staccato Communications 04/0704
• Wisair 05/09

For a complete list of authors, please see page
3.
3
Authors

• Institute for Infocomm Research
• Francois Chin, Xiaoming Peng, Sam Kwok,
  Zhongding Lei, Kannan, Yong-Huat Chew, Chin-Choy
  Chai, Rahim, Manjeet, T.T. Tjhung, Hongyi Fu,
  Tung-Chong Wong
• General Atomics
• Naiel Askar, Susan Lin
• Thales Cellonics
• Serge Hethuin, Isabelle Bucaille, Arnaud
  Tonnerre, Fabrice Legrand, Joe Jurianto
• KERI SSU KWU
• Kwan-Ho Kim, Sungsoo Choi, Youngjin Park,
  Hui-Myoung Oh, Yoan Shin, Won cheol Lee, and
  Ho-In Jeon
• Create-Net  China UWB Forum
• Zheng Zhou, Frank Zheng, Honggang Zhang, Xiaofei
  Zhou, Iacopo Carreras, Sandro Pera, Imrich
  Chlamtac
• Staccato Communications
• Roberto Aiello, Torbjorn Larsson
• Wisair
• Gadi Shor, Sorin Goldenberg

4
Multiband Ternary Orthogonal Keying (M-TOK) for
IEEE 802.15.4a UWB based Alt-PHY
5
Goals

• Good use of UWB unlicensed spectrum
• Good system design
• Path to low complexity CMOS design
• Path to low power consumption
• Scalable to future standards
• Graceful co-existence with other services
• Graceful co-existence with other UWB systems
• Support different classes of nodes, with
  different reliability requirements (and ), with
  single common transmit signaling

6
Main Features

• Proposal main features
• Impulse-radio based (pulse-shape independent)
• Common preamble signaling for different classes
  of nodes / type of receivers (coherent /
  differential / noncoherent)
• Band Plan based on multiple 500 MHz bands
• Robustness against SOP interference
• Robustness against other in-band interference
• Scalability to trade-off complexity/performance

7
Proposed System Parameters
Chip rate 24 Mcps
Pulse / Chip Period 1
Pulse Rep. Freq. 24 MHz
Chip / symbol (Code length) 32
Symbol Rate 24/32 MHz 0.75 MSps
info. bit / sym (Mandatory Mode) 4 bit / symbol
Mandatory bit rate 4 bit/sym x 0.75 MSps 3 Mbps
Code Sequences/ piconet 16 (4 bit/symbol) Code position modulation (CPM)
Lower bit rate scalability Symbol Repetition
Modulation 1,-1 bipolar and 1,-1, 0 ternary pulse train
Total simultaneous piconets supported 6 per FDM band
Multple access for piconets Fixed sequence FDM band for each piconet
8
System Description

• Each piconet uses one set of code sequences for
  different classes of nodes / type of receivers
  (coherent / differential / non-coherent
  receivers)
• 16 Orthogonal Sequences of code length 32 to
  represent a 4-bit symbol
• PRF (chip rate) 24 MHz
• Low enough to avoid significant interchip
  interference (ICI) with all 802.15.4a multipath
  models
• High enough to ensure low pulse peak power
• FEC optional (or low complexity type)

9
Band Plan
BAND_ID Lower frequency Center frequency Upper frequency
1 3168 MHz 3432 MHz 3696 MHz
2 3696 MHz 3960 MHz 4224 MHz
3 4224 MHz 4488 MHz 4752 MHz
4 4752 MHz 5016 MHz 5280 MHz
5 5280 MHz 5544 MHz 5808 MHz
6 5808 MHz 6072 MHz 6336 MHz
7 6336 MHz 6600 MHz 6864 MHz
8 6864 MHz 7128 MHz 7392 MHz
9 7392 MHz 7656 MHz 7920 MHz
10 7920 MHz 8184 MHz 8448 MHz
11 8448 MHz 8712 MHz 8976 MHz
12 8976 MHz 9240 MHz 9504 MHz
13 9504 MHz 9768 MHz 10032 MHz
14 10032 MHz 10296 MHz 10560 MHz
10
Multiple access

• Multiple access within piconet TDMACSMA/CA
• same as 15.4
• Multiple access across piconets CDM FDM
• Different Piconet uses different Base Sequence
  different 500 MHz band

11
Types of Receivers Supported

• Coherent Detection The phase of the received
  carrier waveform is known, and utilized for
  demodulation
• Differential Chip Detection The carrier phase of
  the previous signaling interval is used as phase
  reference for demodulation
• Non-coherent Detection The carrier phase
  information (e.g.pulse polarity) is unknown at
  the receiver

12
Criteria of Code Sequence Design

• The sequence Set should have orthogonal (or near
  orthogonal) cross correlation properties to
  minimise symbol decision error for all the below
  receivers
• For coherent receiver
• For differential chip receiver
• For non-coherent symbol detection receiver
• Energy detection receiver
• Each sequence should have good auto-correlation
  properties

13
Criteria of Code Sequence Design

• To minimise impact of DC noise effect on energy
  collector based non-coherent receiver
• For OOK signaling, the transmitter transmits
  1,-1,0 ternary sequences
• Conventional receive unipolar code sequence
  follows transmit sequence
• After the energy capture in the receiver, the
  noise has positive DC components in each chip
  error occurs in thresholding, especially at lower
  SNR
• This will accumulate noise unevenly in symbol
  decision
• An ideal receive despreading chip sequence should
  then have bipolar chip values, preferrably with
  equal number of 1 and -1 chips
• This, to certain extent, will nullify DC noise
  energy in symbol decision
• This, will also nullify energy components from
  other interfering piconets

14
Base Sequence Set
Seq 1 0 - - 0 0 0 - 0 0 0 - 0 0 0 0 0 0 - 0 - 0 0 - -
Seq 2 0 - 0 - - 0 0 0 0 0 - 0 0 0 0 0 - 0 0 0 0 - - -
Seq 3 0 - 0 - - - 0 0 0 0 - 0 0 - 0 0 0 0 0 0 - - 0 0
Seq 4 0 0 0 - - 0 - - 0 0 0 - - 0 0 0 - 0 0 0 0 0 0 -
Seq 5 0 - - 0 0 - 0 0 0 0 0 0 0 - - 0 - 0 0 0 0 - - 0
Seq 6 0 0 0 - - 0 0 0 0 0 0 - 0 0 - 0 0 0 0 - - - 0 -

• 31-chip Ternary Sequence set are chosen
• Only one sequence and one fixed band (no hopping)
  will be used by all devices in a piconet
• Logical channels for support of multiple piconets
• 6 sequences 6 logical channels (e.g.
  overlapping piconets) for each FDM Band
• The same base sequence will be used to construct
  the symbol-to-chip mapping table

15
Symbol-to-Chip Mapping Gray coded 16-ary Ternary
Orthogonal Keying
Symbol Cyclic shift to right by n chips, n 32-Chip value
0000 0 0 - - 0 0 0 - 0 0 0 - 0 0 0 0 0 0 - 0 - 0 0 - -
0001 2 0 - - - - 0 0 0 - 0 0 0 - 0 0 0 0 0 0 - 0 - 0 0
0011 4 0 0 0 - - - - 0 0 0 - 0 0 0 - 0 0 0 0 0 0 - 0 -
0010 6 0 - 0 0 - - - - 0 0 0 - 0 0 0 - 0 0 0 0 0 0 - 0
0110 8 0 0 - 0 0 - - - - 0 0 0 - 0 0 0 - 0 0 0 0 0 0
0111 10 0 0 0 0 - 0 0 - - - - 0 0 0 - 0 0 0 - 0 0 0 0
0101 12 0 0 0 0 0 - 0 0 - - - - 0 0 0 - 0 0 0 - 0 0 0
0100 14 0 0 0 0 0 0 0 - 0 0 - - - - 0 0 0 - 0 0 0 0
1100 15 0 0 0 0 0 0 0 0 - 0 0 - - - - 0 0 0 - 0 0 0
1101 17 0 0 0 0 0 0 0 0 0 - 0 0 - - - - 0 0 0 - 0 0
1111 19 0 0 0 0 0 0 0 0 0 0 - 0 0 - - - - 0 0 0 - 0
1110 21 0 0 0 0 0 0 0 0 0 0 - 0 0 - - - - 0 0 0 - 0
1010 23 0 0 0 0 0 0 0 0 0 0 0 - 0 0 - - - - 0 0 0 -
1011 25 0 - 0 0 0 0 0 0 0 0 0 0 - 0 0 - - - - 0 0 0
1001 27 0 0 0 - 0 0 0 0 0 0 0 0 0 0 - 0 0 - - - - 0
1000 29 0 - 0 0 0 - 0 0 0 0 0 0 0 0 0 0 - 0 0 - - -
To obtain 32-chip per symbol, cyclic shift the
Base Sequence first, then append a 0-chip in
front
Base Sequence 1
16
Good Properties of the Mapping Sequence

• Cyclic nature, leads to simple implementation
• Zero DC for each sequence
• No need for carrier phase tracking (i.e. coherent
  receiver)

17
Synchronisation Preamble
Correlator output for synchronisation

• Code sequences has good autocorrelation
  properties
• Preamble is constructed by repeating 0000
  symbols
• Long preamble is constructed by further symbol
  repetition

18
Frame Format
2
1
0/4/8
2
n
Octets
Data Payload
Frame Cont.
MAC Sublayer
Seq.
Address
CRC
MHR
MSDU
MFR
Data 32 (n23)
4?
1
1
For ACK 5 (n0)
Octets
PHY Layer
Frame Length
Preamble
SFD
MPDU
SHR
PHR
PSDU
PPDU
19
Transmission Mode
Mode Data Rate (Mbps) Bit / symbol Sym. Rep. TX Sign-aling Receiver type
1a 3 4 1 Ternary - Short Preamble for all receivers - High Data Rate Mode (for Energy Collection receivers)
1b 0.75 4 4 Ternary - Long Preamble for all receivers - Low Data Rate Mode (for Energy Collection receivers)
2a 3 4 1 Binary - High Data Rate Mode (for Coherent / Differential Chip Receiver)
2b 0.75 4 4 Binary - Low Data Rate Mode (for Coherent / Differential Chip Receiver)
20
Modulation Coding (Mode 1)
Binary data From PPDU
Symbol- to-Chip
Bit-to- Symbol
Symbol Repetition
Pulse Generator
0,1,-1 Ternary Sequence

• Bit to symbol mapping
• group every 4 bits into a symbol
• Symbol-to-chip mapping
• Each 4-bit symbol is mapped to one of 16 32-chip
  sequence, according to 16-ary Ternary Orthogonal
  Keying
• Symbol Repetition
• for data rate and range scalability
• Pulse Genarator
• Transmit Ternary pulses at PRF 24MHz

21
Modulation Coding (Mode 2)
Binary data From PPDU
Symbol- to-Chip
Pulse Generator
Bit-to- Symbol
Symbol Repetition
Ternary- Binary
1,-1 Binary Sequence
0,1,-1 Ternary Sequence

• Bit to symbol mapping
• group every 4 bits into a symbol
• Symbol-to-chip mapping
• Each 4-bit symbol is mapped to one of 16 32-chip
  sequence, according to 16-ary Ternary Orthogonal
  Keying
• Symbol Repetition
• for data rate and range scalability
• Ternary to Binary conversion
• (-1/1 ? 1,0 ? -1)
• Pulse Genarator
• Transmit bipolar pulses at PRF 24MHz

22
Auto Correlation Properties for Non-Coherent
Symbol Detection Receiver
23
Cross Correlation Properties for Coherent
Detection Receiver
TxSeqSet RxSeqSet' (Mode 2)
TxSeqSet RxSeqSet' (Mode 1)
24
Differential Multipath Combining
25
Auto Correlation Properties for Differential Chip
Detection Receiver
26
Cross Correlation Properties for Differential
Chip Detection Receiver
DifferentialChip(TxSeqSet) DifferentialChip(RxS
eqSet) (Mode 2)
DifferentialChip(TxSeqSet) DifferentialChip(RxS
eqSet) (Mode 1)
27
Non-Coherent Receiver Architectures (Mode 1)
LPF / integrator
Soft Despread
BPF
( )2
ADC
Sample Rate 1/Tc

• Energy detection technique rather than coherent
  receiver, for low cost, low complexity
• Soft chip values gives best results
• Oversampling sequence correlation is used to
  recovery chip timing recovery
• Synchronization fully re-acquired for each new
  packet received (gt no very accurate timebase
  needed)

28
Auto Correlation Properties for Energy Detection
Receiver (Mode 1)
29
Cross Correlation Properties for Energy Detection
Receiver (Mode 1)
TxSeqSet RxSeqSet '
30
AWGN Performance
31
AWGN Performance

• AWGN performance _at_ 1 PER

_at_ 3 Mbps Non-coherent symbol detection Differential chip detection Energy detection
Mode 1 8.5 dB 13 dB 13.5 dB
Mode 2 7.5 dB 11.5 dB -
32
Basic Data Rate Throughput (Low Rate Modes)

• Useful data rate calculation for 32 byte PSDU (Xo
  0.75 Mbps)
• Symbol Period 1.33us
• Data frame time 38 x 8 / 0.75 405.3 µsec
• ACK frame time 11 x 8 / 0.75 117.3 µsec
• tACK (considering 15.4 spec) 192 µsec
• LIFS (considering 15.4 spec) 640 µsec
• Tframe 1355 µsec
• Useful Basic Data Rate 189.0 kbps

33
Basic Data Rate Throughput (High Rate Modes)

• Useful data rate calculation for 32 byte PSDU (Xo
  3 Mbps)
• Symbol Period 1.33us
• Data frame time 38 x 8 / 3 101.3 µsec
• ACK frame time 11 x 8 / 3 29.3 µsec
• tACK (considering 15.4 spec) 192 µsec
• LIFS (considering 15.4 spec) 640 µsec
• Tframe 963 µsec
• Useful Basic Data Rate 265.9 kbps

34
Basic Data Rate Throughput (High Rate Modes)

• Useful data rate calculation for 127 byte PSDU
  (Xo 3 Mbps)
• Symbol Period 1.33us
• Data frame time 127 x 8 / 3 354.7 µsec
• ACK frame time 11 x 8 / 3 29.3 µsec
• tACK (considering 15.4 spec) 192 µsec
• LIFS (considering 15.4 spec) 640 µsec
• Tframe 1216 µsec
• Useful Basic Data Rate 853.5 kbps

35
Link Budget
36
Ranging and Positioning
37
Asynchronous Ranging Scheme

• Synchronous ranging
• One way ranging
• Simple TOA/TDOA measurement
• Universal external clock
• Asynchronous ranging
• Two way ranging
• TOA/TDOA measurement by RTTs
• Half-duplex type of signal exchange

TOF Time Of Flight RTT Round Trip Time SHR
Synchronization Header
But, High Complexity
Asynchronous Ranging
Synchronous Ranging
38
Features- Sequential two-way ranging is executed
via relay transmissions- PAN coordinator manages
the overall schedule for positioning- Inactive
mode processing is required along the
positioning- PAN coordinator may transfer all
sorts of information such as observed - TDOAs to
a processing unit (PU) for position
calculationBenefits- It does not need
pre-synchronization among the devices-
Positioning in mobile environment is partly
accomplished
Proposed Positioning Scheme
P_FFD3
P_FFD2
TOA
24
TOA
34
RFD
PAN
coordinator
TOA
14
PU
P_FFD Positioning Full Function Device
RFD Reduced Function Device
P_FFD1
39
Process of Proposed Positioning Scheme
TOA measurement
40
More Details for obtaining TDOAs

• Distances among the positioning FFDs are
  calculated from RTT measurements and known time
  interval T
• Using observed RTT measurements and calculated
  distances, TOAs/TDOAs are updated

T12 (RTT12 T)/2
T23 (RTT23 T)/2
T13 (RTT13 T12 T23 2T)
RTT34 T34 T T34
TOA34 (RTT34 - T)/2
RTT24 T23 T T34 T T24
TOA24 (RTT24 - T23 - TOA34 - 2T)
RTT14 T12 T T23 T T34 T T14
TOA14 (RTT14 - T12 - T23 - TOA34 - 3T)

TDOA12 TOA14 TOA24
TDOA23 TOA24 TOA34
41
Position Calculation using TDOAs

• The range difference measurement defines a
  hyperboloid of constant range difference
• When multiple range difference measurements are
  obtained, producing multiple hyperboloids, the
  position location of the device is at the
  intersection among the hyperboloids

42
Positioning Scenario Overview

• Using static reference nodes in relatively large
  scaled cluster
• Power control is required
• Power consumption increases
• All devices in cluster must be in inactive data
  transmission mode
• Using static and dynamic nodes in overlapped
  small scaled sub-clusters
• Sequential positioning is executed in each
  sub-cluster
• Low power consumption
• Associated sub-cluster in positioning mode should
  be in inactive data transmission mode

• Case 1

Cluster 1

• Case 2

Cluster 1
43
Positioning Scenario for Star topology

• Star topology
• PAN coordinator activated mode
• Positioning all devices
• Re-alignment of positioning FFDs list is not
  required
• Target device activated mode
• Positioning is requested from some device
• Re-alignment of positioning FFDs list is
  required

44
Positioning Scenario for Cluster-tree Topology

• Cluster-tree topology

45
Analog Energy Window Bank
46
Ranging Accuracy Improvement

• Technical requirement for positioning
• It can be related to precise (tens of
  centimeters) localization in some cases, but is
  generally limited to about one meter
• Parameters for technical requirement
• Minimum required pulse duration
• Minimum required clock speed for the correlator
  in the conventional coherent systems

High Cost !

• Fast ADC clock speed in the conventional coherent
  receiver is required for the digital signal
  processing

47
Analog Energy Window Bank (1)

• Digital signal processing with fast clock can be
  replaced by using analog energy window bank with
  low clock speed
• Why analog energy window bank?
• Conventional single energy window may support the
  energy detection for data demodulation in the
  operation mode
• However, this cannot guarantee the correct
  searching of the signal position in the timing
  mode (that also means the ambiguity of ranging
  accuracy)
• Analog energy window bank can sufficiently
  support timing and calibration as well as
  operation mode
• Widow Bank Size 4 nsec (smallest pulse
  duration)
• The number of energy windows in a bank 11
• Operation clock speed of each energy window 24
  MHz
• Number of the required energy windows depends on
  the power delay profile of the multipath channel
  (effective multipath components)

48
Analog Energy Window Bank (2)
49
Modifying MAC
50
Modifications of MAC Command Frame (1)

• Features
• Frame control field
• frame type positioning (new addition using a
  reserved bit)
• Command frame identifier field
• Positioning request/response (new addition)
• Positioning parameter information field
• Absolute coordinates of positioning FFDs
• POS range
• List of positioning FFDs and target devices
• Power control
• Pre-determined processing time (T)

Octets 2 1 0/4/8 1 variable variable 2
Frame control Sequence number Addressing fields command frame identifier Positioning parameter Command payload FCS
MHR MHR MHR MAC payload MAC payload MAC payload MFR
51
Modifications of MAC Command Frame (2)

• Frame Control

bits 02 3 4 5 6 79 1011 1213 1415
Frame type Security enabled Frame pending Ack. request Intra- PAN Reserved Dest. addressing mode Reserved Source addressing mode

• Command frame identifier

Frame type value Description
000 Beacon
001 Data
010 Acknowledgment
011 MAC command
100 Positioning
101111 Reserved
Command frame identifier Command frame
0x01 Association request
0x02 Association response
0x03 Disassociation notification
0x04 Data request
0x05 PAN ID conflict notification
0x06 Orphan notification
0x07 Beacon request
0x08 Coordinator realignment
0x09 GTS request
0x0a Positioning request
0x0b Positioning response
0x0c0xff Reserved

• Positioning parameter

Fixed coordinate POS range positioning FFDs Address Target devices lists Pre-determined processing time(T) Power Control
52
Summary

• The proposed system
• Impulse-radio based system coupled with a Common
  ternary signaling allows operation among
  different classes of nodes / type of receivers,
  with varying cost / power / performance trade-off
• Has Band Plan based on multiple 500MHz bands
• Is robust against SOP interference
• Is robust against other in-band interference